Detmolder Sourdough With And Without Yeast - Comparison

For some time I have been looking for German bread formulas, although not systematically. Some time ago I came across [1]Meister Süpke's Blog[2] about sourdough, and setting up a German group at my Son's school gave me finally the incentive to try out Mr Süpke's formulas for bread using the "Detmolder Einstufen-Führung" as I agreed to provide the bread.

Bread according to these formulas (see German Baking Day[3]) can be made with various amounts of wheat and rye using a stiff rye starter at 80% hydration that has been refreshed with 5%-10% mature starter and kept at 24C to 28C for 12 to 18 hours. The Detmolder single step process uses a small amount of commercial yeast in the final dough.

The yeast content raised some questions: Is it necessary? Is the bread loosing sourdough characteristics? Are the bakers in Germany giving up quality in favor of quantity?

From Meister Süpke I got the answer that he could make the bread without yeast added, but in order to get through his schedule he has one hour for the final proof, which is being archieved by adding 1% yeast or less.

Another answer comes from Daniel DiMuzio's book Breadmaking: For some formulas he says one can add up to 0.7% of instant yeast without changing the character of the bread significantly, e.g. p.232, San Francisco Style Sourdough

Well, I wanted to know if the yeast does more than cutting the prooving times short, so I did some comparative baking.

First some pictures.

The 60% Rye loaves:

The 30% and 100% rye loaves:

Conclusion:

Quite surprisingly, there is hardly any noticeable difference in the appearance the bakes with and without yeast. The slightly higher volume of the loaves with altus are due to the additional amount of altus in the dough, I didn't scale those down to 500g.

The loaves with altus were also a bit chewier and tasted more earthy. There was a slight difference between the 60% rye with and without yeast, the sourdough only version being milder. And the 100% rye with yeast maintained a bit of the starter's fruity notes.

The only striking difference loies in the times for the final proof, as shown in the table with the formulas below.

This experiment would suggest that the yeast is not necessary, but it is a great tool to fit this type of bread into a production schedule without the loss of quality. I would be very interested to hear if anyone has different experiences.

Now to some details about the process:

Starters:

All the breads in this comparison call for a rye starter with 80% hydration. For the 60% rye batch I used wholegrain rye flour, for the others I used light rye flour (Type 997). I am maintaining a liquid wholegrain rye "mother" at 200% hydration, which is very reliable and worked well as a seed culture.

The starters were made in two elaborations (same process for wholegrain and light rye starters):

This way the original liquid "mother" makes up just 1% of the starter - no worries about the wrong hydration or grain. The starters rose well to about four times their original volume, and had a nice tangy smell. The light rye starter developed a very nice fruity-flowery smell.

The altus (fresh "old bread", 80% rye) has been added to the water for the 2nd elaboration to soak. No aditional water added. There was very little difference in the starter consistency with and without altus.